Air compressor



June 17, 1941. J, J, WYDLER AIR COMPRESSOR Filed Feb. 15, 1940 R O T N EV m t/OHA/V/V U. WYD ER ATTORNEY Patented June- 17, 1941 AIR. COMPRESSORJohann J. Wydler, Westfield, N. J., assignor, by

mesne assignments, to Cities Service Oil Company, New York, N. Y., acorporation of Pennsylvania Application February 15, 1940, Serial No.318,985

11 Claims. (Cl. 230-955) This invention relates to an improved apparatusfor deriving energy from. engine exhaust gases and utilizing such energyfor compressing air for supercharging the engine.

The gas exhaust period of the cycle of any four cycle internalcombustion engine cylinder consists of two parts. During the first partof the exhaust period, just after the exhaust valve has been opened, a.substantial proportion (roughly 50%) of the total weight of gas in thecylinder i rapidly discharged as a high pressure puff wave movingoutwardly from the cylinder into the exhaust manifold at high initialpressure and at high velocity. During the latter part of the exhaustperiod the remaining portion ofthe exhaust gases leave the cylinderunder a relatively low pressure head and'mode'rate velocity in front ofthe advancing piston; this period of the cycle being referred to as thestroke period of the exhaust.

The present invention i directed to an improvement on that described inthe copending joint application of Robert G. Griswold and Johann J.Wydler, Serial No. 240914, filed November 12, 1938, for Enginesupercharging. According to the invention of the aforesaid jointapplication, a displacement compressor is employed as the medium forcompressing air for supercharging one cylinder of a multicylinder,

four cycle internal combustion engine by means i of the pressure energyof the coinciding puff discharge wave of exhaust gases leaving anothercylinder of the engine which is operating 360 apart in crank angle phasewith respect to the first cylinder. This displacement compressoroperates as a gas piston pump or compressor in which a body of air firstintroduced into the pump chamber is compressed and then discharged by anonturbulent stratified layer or wave of hot exhaust gases under higherpressure moving forward in direct contact with and displacing the air inthe pump chamber without substantial mixing with and contamination ofthe air by the gas.

The principal object of the present invention is to provide an improvedapparatus for deriving energy from the waste exhaust gases of aninternal combustion engine and using such energy for compressing air.

A feature of the present invention is that an improved design ofdisplacement compressor or pump is provided having relatively rotatablevalves and housing therefor, together with mechanism for adjusting thearea and timing of the valve ports controlling transfer of atmosphericand supercharge air and exhaust gases. A preferred compressor designembodies a pair of rotary cylinder valves and adjustable sleevestherefor, located respectively at the hot and cold gas ends of eachdisplacement compressor. The single valve at the cold end is designed tocontrol and properly time the periods of engine atmospheric air intake,pump discharge of compressed air, and air scavenging of the pump. Thevalve at the hot end operates to control and time the periods of pumpintake'of engine puff exhaust gases, discharge of exhaust gases from thepump, and transfer of engine stroke exhaust gases to suction aspirators.

The air compression and displacement period in the operating cycle ofeach displacement compressor is followed by a scavenging period duringwhich the exhaust gases are discharged from the compressor and thecompressor is scavenged with atmospheric air. A major part of the energyfor such scavenging operation is preferably derived from the exhaustgases which are discharged from the exhausting engine cylinder duringthe stroke part of the cylinder exhaust cycle. To provide an additionalscavenging effect, the gas exhaust ducts of a pair of dispacementcompressors are preferably interconnected by concentric twin nozzles,each of which operate to develop repeated suction impulses at therespective compressor exhaust ports during one and the same scavengingperiod.

With the above and other objects and features in view, the inventionconsists in the improved apparatus for compressing air and forsupercharging a four cycle internal combustion engine, which ishereinafter described and more particularly defined by the accompanyingclaims.

The invention will hereinafter be described with particular reference tothe accompanying drawing, in which:

Fig. I is a horizontal sectional view of a preferred design ofdisplacement air'compressor;

Fig. II is a vertical sectional view of the air transfer ports andcontrol valve therefor, taken on the line IIII of Fig. I;

Fig. III is another vertical sectional view through the air transferport end of the compressor, taken on theline IIIIII of Fig. I;

Fig. IV is another vertical cross sectional view through the hot gastransfer port end of the compressor, taken on the line IVIV of Fig. I;

Fig. V is still another vertical cross sectional view through the hotgas transfer port end of the compressor, taken on the line VV of Fig. I;

Fig. VI is a diagrammatic view illustrating the hook-up of all sixcylinders of a six cylinder engine, through a pair of exhaust manifoldsand a pair of intake manifold and carburetors, with a pair ofdisplacement compressors;

Fig. VII is a diagrammatic view illustrating by means of arrows the flowof gases during the re expansion period in the operating cycle of theupper displacement compressor shown in Fig. VI. In Fig. VI the directionof flow of air and gas during the pun supercharging period i indicated;

Fig. VIII is a diagrammatic view of the atmospheric air intake period ofthe scavengingcycle of the upper compressor illustrated in Fig. VI, andof the simultaneous atmospheric air intake of the engine cylinder nextin cycle with the pump; and

Fig. IX is a perspective view of the three-sectioned adjustable sleevewhich journal the rotary valve at the air transfer end of thedisplacement compressor.

The apparatus illustrated diagrammatically in Fig. VI includes a sixcylinder four stroke cycle internal combustion engine 2!] and twodisplacement air compressors 22 and 24 which are operatively connectedfor compressing air at the expense of energy derived from the engineexhaust gases, and utilizing the compressed air for supercharging theengine. L1 its broadest scope, however, the invention is not limited tothe use of the compressed air for engine supercharging; nor is theinvention limited in application to an engine having six cylinders.

In Fig. VI the cylinders of a six cylinder, four cycle engine have beennumbered respectively I, 2. 3, 4, and 6; and cylinders l, 2 and 3 havebeen shown with their exhaust ports connected through an exhaustmanifold 26 and conduit 28 to a hot gas inlet valve housing 38 at oneend of a compressor 22; while the exhaust ports of cylinders 4, 5 and 6have been shown as connected through an exhaust manifold '32 and conduit34 to the hot gas inlet valve housing 35 at one'end of compressor 24.Likewise the intake ports of cylinders I, 2 and 3 have been shown asconnected through an intake manifold 35 and carburetor 33 to an airvalve housing 39 at the other end of compressor 24; while the intakeports of cylinders 4, 5 and B have'been shown as connected through anintakemanifold 1D, carburetor G2 and pipe 45 to an air valve housing Mat the other end of compressor 22 (Fig. I)

Thecylinders of a multicylinder engine must be paired in practicing thepreferred supercharging operation of this invention, so that the energycarried by the exhaust gas discharged from one cylinder of a pair can beutilized for compressin the air introduced into the other paired'cylinder at the end of its intake period. During the first part of theair intake period for each cylinder air is supplied at atmosphericpressure. The pistons in each cylinder of a pair, such as 2 and 5; passsimultaneously through their topand bottom dead centerposf.tions.However, the

power strokes of the pistonsare 360 crank angle apart in phase. In theof engines having an uneven number of cylinders; as for examplenine'cylinders, the dead center positions of the pistons in pairedcylinders are not exactly together (for example 40 apart) and thereforethe power strokes 'are'apart in phase less than30 (for example 320).

" The displacement compressors or'pumps 22 and '24 are identical indesign. Each has a cylindrical main housing'48 which preferably hasalength several times its maximum internal diameter (Fig. I). Valvehousings 30 and 44 of compressor 22 are shown as attached respectivelyto the opposits ends of housing 43 as extensions thereof. A hollow valvedrive shaft 58 is mounted within the housing d8, extending from end toend thereof along the longitudinal axis of the compressor. Displacementand compression chamber 52 of the compressor is of annular cross sectionand lies between the inner wall of the housing 38 and the outercircumference of the shaft 50. The chamber 52 preferably has a cubiccapacity only sufiicient to handle the volume of hot gas which isdischarged from a single engine cylinder during the first or pulfportion of its exhaust, and to compress only the air with which acylinder is supercharged at the end of its air intake period. Withinthat extension 30 of the compressor 22 into which hot exhaust gases areadmitted from exhaust manifold 28, there is mounted an aperturedcylindrical sleeve or bushing 54 within which is journalcd a portedcylinder valve 56. The hub of valve 55 is keyed to shaft for rotationtherewith. Within the valve housing 44 at the opposite end of thecompressor, there is assembled a multi-sectioned apertured cylindricalsleeve or bushing 58 within which is journaled a ported cylinder valveBil. Valve 60 has a hub which is preferably fastened to shaft 50 by aset screw for rotation therewith. The imperforate web extensions of thehubs of valves and which attach the cylindrical valve walls to the hubs,form end wall closures for the compressor chamber 52.

Referring to Figs. I, IV and V, it will be seen that that end of thecompressor 22 into which hot exhaust gases are introduced from theexhaust manifold 25 houses an annular gas by-pass chamher 62 which is inpermanent communication with the atmosphere through a funnel 63 .and anaspirator pressure nozzle 5 The hot gases from manifold 26 are conductedby conduit 28 to a permanent aperture 56 in the wall of valve housing38. That portion of sleeve'5 l which overlies housing aperture 65 isalso provided with two apertures 61, 68, which register with theaperture '55. Valve 55 is provided with a pair of identical ports 2'5 inopposite sides of that portion ofits cylindrical wall which is rotatablyaligned with sleeve aperture 68. Sleeve 54 and valve housing so are alsoprovided respectively with registering apertures 1|, 'l2, which areadapted to cornmunicably connect the interior of housing 33 and sleeve5% with a gasdischarge funnel 14. That portion of the cylindrical wallof valve 56 which lies to the right of the hub Web, as viewed in I. isalso provided with a pair of identical oppositely disposed wall ports 15(Fig. V), which on rotation of the valve about 30-40 clockwise from theposition illustrated in Figs. I and V, will come into register with theapertures 66 and 61.

Valve housing 44 at the opposite end of the 'cnmnressoris permanentlyapertured at 11 and 18 (Figs. I, If and III). Sleeve 58 is also providedwith wall apertures wand which normally register with apertures 71 and18, respectively.

Valve 60 is provided with a pair of identical ports 2'92 in oppositesides of that portion of its cylindrical wall which is rotatably alignedwith apertures T1 and I8. Vfllen valve 6!! is rotated about 90 clockwisefrom the position illustrated in Fig. III, its ports 82 are moved intofull register with other apertures as and 85 located respectively in thewalls of sleeve 5B.and housing 44. An air by-pass chamber 85 is formedwithin valve housing 44 to the le'tt of the hub web of the valve asviewed in Fig. I. Chamber B6 is permanently connected to atmospherethrough an air supply conduit 88 and filter 90. As shown in Fig. II,that portion of the cylindrical wall of valve 60 which lies to the leftof the hub web, as viewed in Fig. I, is provided with a pair ofoppositely disposed identical ports 92 which, on rotation of the valveabout 90 clockwise from the position illustrated in Figs. I and II, willcome into full register with apertures I8 and 00.

Thus with the shaft 50 and valves 56 and 60 in place, the displacementcompressor comprises a pair of short annular chambers 62 and 86 locatedat opposite ends thereof, each chamber being permanently connected tothe outside atmosphere, together with a long displacement aircompression chamber 52 of annular cross section lying between shaft 50,housing 48 and the hubs of valves 56 and 60.

The engine is of course equipped with the usual air and fuel valves andexhaust valves for each cylinder intake and exhaust port. Combustionwithin any cylinders of the engine is initiated by means of a sparkplug, the timing of which is controlled by a distributor. The engineintake and exhaust valves and the distributor are all actuated from theengine through a cam shaft which operates at half the speed of theengine crank shaft. The drive shafts 50 for the valves 56 and 60 in eachof the compressors 22 and 24 are driven at three-fourths the speed ofthe engine through suitable drive mechanism such as the chain and geardrives 94, which are illustrated in Figs. I and VI.

The valve drive shaft 50 for each compressor is journaled at oppositeends of the compressor on ball bearings I and I3I (Fig. I). An importantfeature in the design of the compressor is the provision of means forlimiting transfer of heat from the hot gas end to the cold air transferend of the compressor and to the valve shaft bearings on the hot side.This protection may include a water jacket I32 for the main section 48of the compressor, together with an annular water cooled compartment I34around or adjacent bearing I3I. Means are also shown for cooling thebearing I3I at the hot gas intake side of the compressor by airventilation. To effect this, apertures I35 are provided in that portionof the wall of shaft 50 which rotates in air intake chamber 86.Additional wall apertures I36 are centered in a chamber I31 within whichthe bearing I3I is mounted. Apertures I38are also ported out fromchamber I31 through the compressor housing, and the ends of the hollowshaft 50 are closed by plugs I39. By this arrangement, a cooling draftof air can enter chamber I31 from the outside atmosphere and flow thencethrough the hollow bore of shaft 50 into air intake chamber 86 duringthat portion of the cycle of each engine cylinder during which air atatmospheric pressure is being taken into the cylinder. To seal thebearing I3I against contact with the hot gases entering the chamber 62of the compressor, a partition stufling box I40 is mounted betweenchamber 62 and air chamber I31. Essentially this stuffing box comprises,a housing for a plurality of shim stock seal rings I4I encircling theshaft and separated from each other by spacing rings I42. All the ringsare prevented from rotating with the shaft by a key; however, they arefitted loosely with respect to each other and with a minute clearance onIII the shaft to permit true self-centering adjustment on the shaft. 7

When operating engine 20 with supercharging, the air supply end of thecompressor with its rotary valve 60, must function to: (a) transfer-airat atmospheric pressure through chamber 86 to the intake port of acylinder operatively connected to the compressor during the major partof the cylinder intake period (Fig. VIII) (b) cut' off the atmosphericair transfer and transfer compressed air from the compressor chamber 52as a puif supercharging wave through the carbureter into the intakingcylinder at the end of the intaking period (Figs. I, III and VI); (0)simultaneously with at least part of the atmospheric air transfer period(a), admit scavenging air from atmosphere through ports 85, 84, 82, intothe compressor chamber 52 (Fig. VIII). Likewise, the hot exhaust gasreceiving end of the compressor with its rotary valve 56 must functionto: (d) introduce the first or pui'l exhaust gas discharge from acylinder operatively connected to the compressor into the chamber 52during the supercharging period (b) (Figs. I, IV and VI); (e) cut-offtransfer of exhaust gas to chamber 52 and switch the exhaust gasdischarged during the second or stroke portion of the engine exhaustinto the aspirator pressure nozzle 64 (Figs. VII, VIII); (f)simultaneously with actions (0) and (e) open the connection between 52and exhaust discharge funnel 14 for the purpose of scavenging thecompressor before beginning a new cycle. When operating the enginenormally without supercharging, the air supply end of the compressor andvalve 60 should also function to (9) transfer atmospheric air to theengine intaking cylinder connected therewith throughout the entireintake period.

In order to enable the air supply end of the compressor and valve 60 tofunction as specified under a, b, c, and g, sleeve 58 has been designedin three ring sections, I44, I46 and I48 (Fig. IX), and two of thesesections I44 and I 46 have been made rotatably adjustable within housing44 for the purpose of varying the length of time during which sleeveports are in position to allow air passed by valve ports 92 to betransferred to conduit 46. Sleeve sections I44 and I46 are providedrespectively with handles I50 and I52 (Fig. I) extending to the outsideof housing 44 through arcuate slots I54 and I56 in the housing.Actuating mechanism I58 is provided attached to handles I50 and I52 ofthe sleeve sections I44 and I46 at the air intake ends of bothcompressors 22' and 24 whereby to simultaneously move sections I44 andI46 of the sleeve 58 in each compressor in opposite directions to varythe size of openings 80. Timing adjustments of the atmos pheric airintake periods can thus be made by means of sleeve 58, as well as byshifting the point of attachment of valve 60 to shaft 50 by the setscrew. The hot valve 56 is preferably keyed to shaft 50, but the timingof the gas exhaust periods of the compressor may be varied by shiftingthe angular position of the shaft 50 and valve 56 relative to the enginecrank shaft at the chain drive sprocket 94.

In Fig. II, the two apertures'60 in the wall of the left hand side ofsleeve 58 as viewed in Fig. I, are illustrated as of unequal area. Fig.IX illustrates the construction whereby the relative areas of these twoapertures can be varied by rotating sleeve segments I44 and I46 inopposite directions. Sleeve segment I44 consists of a ring to which isattached a cylinder segment I60 which in the preferred design subtendsan arc of 115. Segment I69 extends to the right of ring M24 as viewed inFigs. I and IX, with its outer edge forming a close sliding fit withring I45. Ring I46 carries a corresponding cylinder segment I62 whichalso subtends an arc of 115 and which extends to the left, as viewed inFig. IX, with its outer edge in close sliding relation to ring I44. Thusthe apertures 80 are defined as to length and width by the rings I44 andH16 and their segments I62 and I62. Similarly, apertures 84 and I9 atthe right hand side of sleeve 58 may be varied as to relative areas byrelative movement of ring I45 with respect to stationary ring I48.Referring to Fig. IX, it will be seen that ring I68 is provided with twooppositely disposed cylinder segments !63, I55, one of which in thiscase subtends an arc of 48, and the other an arc of 42. The ends ofsegments I33 and I54 extend to close sliding relation with ring I26.Ring I46 carries at its right hand side as viewed in Fig. IX, a pair ofoppositely disposed cylinder segments I65 and I56, one of which subtendsan arc of 43, and the other an arc of 42. Thus the rings Hi8 and H52,together with their segments I63, I64, I55 and I66 afford the means forvarying the lengths of the air scavenging period and of the compressedair discharge period for the compressor.

Valves 5B and are designed to rotate with very small clearance withinthe sleeve bushings 54 and 58. To reduce conduction of heat by the metalparts from the hot ends of the compressor, a heat dam IE8 is disposedbetween housing sections 30 and 48. Other heat dams are provided betweenchamber 62 and the housing of bearing I3I, and circumferentially betweenthe retainer of bearing I3! and the housing.

It'is possible to obtain wide adjustments in the timing and intensity ofthe aspirator effect when operating with a multi-cylinder engine. Theaspirator jet Ed has its greatest force during the re-expansion periodin the cycle of the compressor, and reaches a second and smaller peak atabout the mid-portion of the exhaust stroke A of the piston in theexhausting engine cylinder. Considerable benefit has been obtained byoperation of the aspirator 64 prior to the instant of cut-off oftransfer of exhaust gases into chamber 52 by valve 56,

Referring to-Fig. VI, there has been illustrated diagrammatically anarrangement of multiple aspirator jets and interconnected compressordischarge conduits ld, by means of which it is possible to utilize moreeffici ntly suction impacts developed by one compressor discharge forpromoting eificient scavenging of a second compressor interconnectedtherewith. Thus, in Fig. VI, the exhaust lines It of compressors 22 and24 are interconnected at the throat I69 into a common discharge funnelI28. Each conduit "I i terminates at the throat in the equivalent of asecondary aspirator nozzle adapted to develop suction in the otherexhaust line. By this arrangement, the tail end of the scavenging periodin one compressor 22 is most efficiently supplied with an additionalsuction impact produced by the high velocity discharge of gases duringthe re-expansion portion of the operating cycle of compressor 24.Similarly, the tail end of the scavenging period in compressor 24 isboosted by the suction impact developed by high velocity discharge ofgases from compressor 22. The secondary aspirator thus provided at thethroat I69 is made up of two concentric orifices, each having an areaequal to or slightly smaller than the area of its respective exhaustpipe I4. The cone III] of the secondary aspirator is of gradual Wideningcross-sectional area ultimately leading to atmosphere, preferably by wayof a mufiling device. I

When cylinder I is operatively connected to the compressor 22 during itsexhaust period, the putt exhaust gas discharge wave which enters thecompressor chamber 52, compresses the air charge within the compressorand interconnected spaces until the total mass of air and gas hasreached a balancing pressure. If at the same time cylinder 6 isoperatively connected to the compressor, valve 68 of the compressoroperates to cut oh the supply of atmospheric air to cylinder 6 and toconnect the compressor space 52 with the intake port of the cylinder topermit transfer of compressed air from the compressor through thecarbureter and intake manifold into this cylinder during the latter partof its intake period and during the period when the piston therein isjust starting its compression stroke. When the piston in the airintaking cylinder 5 reaches a point in its travel about 40-60 crankangle beyond bottom dead center position on the compression stroke, itsair intake valve closes. During this period of transfer of air from thecompressor to the cylinder 6 substantially the entire original aircharge for the compressor is discharged under substantially the peakpressure impressed thereon by the puff exhaust Wave from exhaustingcylinder I of the engine. At the instant that the intake valve ofcylinder 6 closes, the interior of the compressor 22 is stillcommunicably connected with the intake manifold fill. However, at thisinstant the valve 56 of the compressor operates to cut off any furthersupply of hot exhaust gases from cylinder I to the compressor, and toopen the compressor for discharge of gas therefrom to atmosphere throughthe exhaust funnel 14.

As soon as compressor valve 56 opens to discharge gas into funnel 14, arapid discharge takes place as a result of suction developed by thefinal transfer of exhaust gases from cylinder I to the aspirator nozzle64 during the stroke portion of the cylinder exhaust period. The suctionthereby developed quickly reduces the pressure within the compressor toa point below atmospheric pressure. This pufi exhaust period extends inthis particular example over 88 crank angle, and the pufi intake portsstay open over crank angle, thus allowing for re-expansion Within thecompressor over a period of 120 minus 88 equals 32 crank angle.

At the end of the re-expansion period valve 68 disconnects space 52 fromthe intake manifold and carbureter and brings ports 82 into registerwith atmospheric air intake ports 84 and 85, thus permitting influx offresh scavenging air to the compressor preparatory to operation of thecompressor on a second cycle, during which the exhausting cylinder iscylinder 3, and the liylinder taking in supercharge air is cylinder InFig. I the compressor ports are shown at the position which they occupyduring the period of pufi supercharging. The positions of the portswhich are illustrated in Figs. II to V inclusive, represent the instantabout 45 crank angle after the beginning of the puil period, i. e. whenthe exhaust gas inlet port H! of the compressor is fully open. At thistime the puff air discharge port 82 has still about 11 crank angle tomove to reach full open-position.

It will be appreciated that the air scavenging of the compressor can'be'efiected without devel: oping suction by means of an aspirator, andwithout supplying scavenging air at atmospheric pressure. Thusscavenging air may be supplied to the air intake end of the compressor,under the positive pressure furnished by a fan or blower. Likewise theinvention is not limited in other respects to the specific apparatuswhich has been described. For example, the invention contemplates acompressor in which the casing or shell may be rotatable and thecylindrical valves stationary, and in which other means may besubstituted for those specifically described whereby to vary the timingand/or area of the gas and air transfer port openings.

The invention having been thus described, what is claimed as new is:

1. In a gas displacement air compressor, an elongated tubular housing,individual pressure gas inlet and waste gas discharge ports at spacedpoints in said housing adjacent one end thereof, individual atmosphericair inlet and compressed air discharge ports at spaced points in saidhousing adjacent its other end, a valve unit mounted coaxially with saidhousing for relative rotation with respect thereto and having tubularside walls positioned and dimensioned to form a close journal fit withthe ported sections'of the housing, and ports in the valve unitrotatably aligned respectively with the housing gas inlet and dischargeports and with the housing air inlet and discharge ports, said valveports being so disposed as to communicably connect the housing gas inletand air discharge ports at one period of the compressor cycle, and tocommunicably connect the housing gas discharge and air intake ports at alater period of the cycle.

2. A displacement compressor as defined in claim 1, including a pair ofcylindrical apertured sleeve bushings Within which the ported sectionsof the valve unit at each end of the housing are respectively journaled,the apertures in the bushings being adapted to register with the portsin the housing.

3. In a gas displacement air compressor, an elongated tubular housing, adisplacingv gas inlet and two gas discharge ports at peripherally spacedpoints in the wall of said housing adjacent one end thereof, a pair ofair inlet ports and a compressed air discharge port at peripherallyspaced points in the wall of said housing adjacent its other end, avalve unit mounted coaxially within said housing for relative rotationwith respect thereto and having tubular side walls positioned anddimensioned to form a close journal fit with the ported sections of thehousing, and two pairs of wall ports in the valve unit rotatably alignedrespectively with the housing gas inlet and discharge ports and with thehousing air inlet and discharge ports, said valve ports being sodisposed that individual ports of each pair respectively register withthe housing gas inlet and air discharge ports at one operating positionof the valve unit, and 'at a later operating position the paired portsat each end of the valve unit register respectively with the housing gasdischarge ports and the air inlet orts.

p 4. A displacement air compressor as defined in claim 1 including acylindrical apertured sleeve bushing at the air inlet and discharge portend of the housing within which the corresponding end of the valve isjournaled, said sleeve comprising at least two relatively rotatable ringsections arranged for adjusting the areas and position of the apertures.j

5. A displacement compressor as defined in claim 1 including wallclosures for each end of the housing and end walls at each end of thevalve unit, gas and air bypass chambers located respectively between theends of the valve and the adjacent housing end closures, two additionalpairs of housing wall ports opening respectively into the air and gasbypass chambers at spaced points in the walls thereof, and wallextensions of the valve unit at each end thereof beyond the adjacent endwall arranged respectively for periodically making and interruptingcommunication through the air and gas bypass chambers between thehousing wall ports opening therein.

6. A displacement compressor as defined in claim 1 togethen with anaspirator having a suction throat communicably connected with thehousing gas discharge port and having a compressor nozzle mounted insaid throat, and a communicable bypass connection under the control ofthe compressor Valve unit between the housing gas inlet port and theaspirator pressure nozzle.

7. A displacement compressor as defined in claim 1 in which the ends ofthe housing in which the gas and air inlet and discharge ports arelocated are constructed as detachable tubular segment extensions of themain housing, and in which the main housing 'is water jacketed.

8. A displacement compressor as defined in claim 1 together with ahollow rotatable shaft mounted longitudinally within said housing onwhich said valve unit is rotatably mounted, bearings for the shaft ateach end of the housing, and a stuffing box arranged as a partitionbetween the gas inlet port and the bearings at the gas inlet end of thehousing.

9. A displacement compressor as defined in claim 1 in which that end ofthe housing which contains the gas inlet and discharge ports isconstructed as a detachable tube segment extension of the housing, andin which heat dams in the form of knife edge joints are provided at thepoints of contact of the housing and said housing extension.

10. In a gas displacement air compressor, an elongated tubular housing,individual gas inlet and discharge ports at spaced points in the wall ofsaid housingadjacent one end thereof, individual air inlet and dischargeports at spaced points in the wall of said housing adjacent its otherend, and a valve unit mounted coaxially within said housing for rotationwith respect thereto, said valve unit having a rotatable shaft mountedlongitudinally within the housing, tubular side walls positioned anddimensioned to form a close journal fit with the ported sections of thehousing, imperforate webs at each end of the valve unit connecting theside walls to the shaft, and wall ports in the valve unit rotatablyaligned respectively with the housing gas inlet and discharge ports andwith the housing air inlet and discharge ports, said valve ports beingso disposed relative to each other and to the housing ports that onevalve port registers with the housing air discharge port while anotherregisters with the housing gas inlet port, and so that the housing airinlet and gas discharge ports are communicably connected byco-registering valve ports only when the gas inlet and air dischargeports of the housing are blanked 01f by the valve.

11. A gas displacement compressor as defined in claim 1 in which theseveral housing ports and valve ports are 50 positioned and dimensionedwith respect to each other that the housing air discharge port iscommunicably connected to the compressor for a short're-ex'pansionperiod after the gas inlet port has been closed and after the gasdischarge port has been opened and that the housing air inlet port isopen only when the air discharge port is closed and when the gas inletport is also closed.

JOHANN J. WYDLER.

